Because the speed of web offset printing presses has continued to increase (web speeds can exceed 4200 ft/min.), manufacturers of printing presses have continued to search for ways to reduce the rotating mass of the rollers in the presses. One way this is accomplished is by using carbon-fiber cores for the rollers of the printing press, which can reduce the weight of the rotating mass considerably and at least up to approximately 85% when compared to using steel rollers.
In for example, an offset printing press, there are basically three materials that are presently applied to the surface of a metal or steel roller core: rubber, nylon or chrome.
Other known disadvantages of a metal or steel core roller include the difficulty of replacement of such rollers which can exceed seven feet in length, can be very heavy and may cause injuries, such as crushed fingers, of those doing the replacing of a roller in a printing press.
Heretofore, it has been known to provide metal, usually made of steel, printing press rollers have an outer coating of nylon or chrome applied thereto. These steel rollers with nylon or chrome outer surfaces were usually used in the press inking system. However, no such nylon or chrome outer coatings have been known to been successfully applied to carbon fiber rollers. It is known that a roller made of carbon fiber would be lighter in weight, stiffer, and more easily handled than would be a steel roller. It is known to use such carbon fiber rollers in presses, but without a nylon or chrome outer surface thereon. Such prior art carbon fiber rollers have had usually a rubber outer surface thereon. The outer surface of the carbon fiber roller, itself, does not possess the necessary properties or attributes to work successfully in a printing press, and particularly in the inking system, where heretofore nylon or chrome outer coated steel rollers were used. For example, in the inking and water systems of certain types of presses, a nylon or chrome surface is needed. Heretofore, it has not been possible to successfully put such nylon or chrome outer surface onto a carbon fiber roller core.
In the conventional method for coating a metal steel core rollers with nylon, a fluidized bed, is a preferred method of applying powders, such as nylon, to a metallic surface. In this process the steel roller to be nylon coated is first heat sunk for a predetermined period of time in an oven, correlated to core size/mass, to reach a temperature of approximately 550° F. The hot metallic roller is then removed from the heating oven and rotated in a fixture inside the fluidized bed until the nylon melts onto and coats the metal core, to the proper thickness. Such procedure will not work with a carbon fiber roller core as such heating would also destroy the carbon fiber core.
Similarly a chrome surface can be provided onto a metal or steel roller by conventional plating it onto the steel roller directly or indirectly with intervening layers of copper and/or nickel.